SNP Shot: Genomic Insights

Adenosine deaminase (ADA) deficiency is a genetic condition that impairs the immune system, resulting in severe combined immunodeficiency (SCID). Individuals with SCID have extremely limited immune defenses against bacteria, viruses, and fungi. Consequently, they are highly susceptible to recurring and persistent infections, which can be severe or fatal. These infections are frequently caused by opportunistic organisms that generally do not cause disease in individuals with healthy immune systems.

Key symptoms of ADA deficiency include pneumonia, persistent diarrhea, and extensive skin rashes. Affected children typically experience significantly slower growth compared to their healthy counterparts, and some may exhibit developmental delays.

The majority of individuals with ADA deficiency are diagnosed with SCID within the first six months of life. Without medical intervention, these infants typically do not survive beyond the age of two. In approximately 10 to 15 percent of cases, the onset of immune deficiency is delayed, occurring between 6 and 24 months of age (delayed onset) or even in adulthood (late onset). In these later-onset cases, the immune deficiency is generally less severe, primarily manifesting as recurrent upper respiratory and ear infections. Over time, affected individuals may develop chronic lung damage, malnutrition, and other health complications.

Inheritance:

ADA deficiency follows an autosomal recessive inheritance pattern. This means that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. The parents, who each carry a single copy of the mutated gene, are typically unaffected and do not exhibit any symptoms of the condition.